Process and means for making color-printing plates



March 17, 1925. 1,530,076

J. A. H. HATT PROCESS AND MEANS FOR MAKING COLOR PRINTING PLATES Filed July 8, 1921 7 77! F'1 7 6 F2 ll 7 5;; 3 4 4 WHITE NAHUM RED YELLOW c CYAH W T KEEN BLUE OLE BLACK 1 J E INVENTOR ,6 1'

ments in Processes and Means for Makin Patented Mar. 17, 1925.

UNITED STATES PATENT "oF'Flca.

JOSEPH a. n. HATT, or m YORK, N. Y.

PROCESS AND MEANS FOR MAKING COLOR-PRINTING I 'LATESU Application filed July 8, 1921. Serial No. 483,235.

To all whom it may concern:

Be it known that I, JOSEPH A. H. .HATT, a citizen of the United States, residing in New York, in'the county and State of NewXork, have made certain new and useful Improve- Color-Printin Plates, of which the following is a speci cation.

The invention relates to aprocess for making by photography printing plates for color printing which are of true or correct color value and more especially to such a process wherein there are produced photographically corrective plates which are used together with ordinary color negatives to produce printing plates for the various colors having true or correct color values.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and c'ombinations drawings, and which are employed in the process of the present invention and which themselves are also included as a part of the invention.

Of the drawings 2-- ,Fig. 1 is a diagrammatic representation of a color chart, employed by way of example as the original or the copy from which the printing plates are to be made.

Relating to the magenta color plate.

Fig. 2 is a similar diagrammatic representationof a mask negative, which is employed in my process in correcting the magenta plate;

Fig. 3 is a similar diagrammatic view of the corrective plate forthe magenta printing plate, which plate is made through the mask negative shown in Fig. 2;

Fig. 4 is a similar diagrammatic view of the ordinary negative (of incorrect or untrue color value) for the magenta printing plate; v 1

Fig. 5 is a similar diagrammatic view of a true or correct color value ne ative for the magenta printing plate made y using the of Fig. 3.' Relating to malcz'ng the yellow color plate.

Fig. 6 is a similar diagrammatic view of a corrective plate for the yellow printing plate, which also is made through the mask negative of Fig. 2, and corresponds relativelylto the plate of'Fig. 3 forthe magenta co or;

Fig. 7 is asimilar-diagrammatic view of a corrective plate made through the mask negative of Fig. 4;

Fig. 8 is a similar diagrammatic view of the ordinary negative of untrue or incorrect color value) made or the yellow printing plate;

Fig. 9 is a diagrammatic View of a true or correct color negative made by using the corrective plate of Fig. 7 and the negative of Fig. 8.

work.

Fig. 10 is a diagrammatic view showing a corrective plate for the magenta color negative in four color work, and corresponds to g negative of Fig. 4 with the corrective plate Relating to making plates for four-color the plate ofFig. 3 except that the black in Fig. 1.0 is partly dense or opaque;

Fig. 11 represents diagrammatically a true and correct color-tone negative for the magenta color plate in four color work, made from the corrective plate of Fig. 10 and the primary negative of Fig. 4 a

Fig. 12 represents diagrammatically a corrective plate for the yellow printing plate in four color work, similar in characteristics to that of Fig. 10;

Fig. 13 represents diagrammatically atrue and correct tone negative for the yellow color printin plate made fromthe corrective plate 0 Fig. 12 and the negative of Fig. '8 for four color work;

Fig. 14 represents diagrammatically acorrective plate for the black in the four color work; and

Fig. 15 represents diagrammatically .the corrected black negative for making the black color plate for four color work.

In the drawings which are presented herewith as examplary and explanatory of the invention, the colored original or copy is shown as a color chart, in which the primary colors and some of the secondary colors are in separate blocks or sections. This is necessary in order to clearly and concisely set out the invention, which would not be possible, or at least practicable, with the ordinary or usual originals or copy, such as colored pictures and the like, wherein the various primary and secondary colors are scattered and blended to a greater or lesser degree throughout the design. Also for clearness and ease of comparison, the negatives and positives are not shown in reverse, for as shown, the comparisons of color areas and relative degrees of opacity are much more easily and readily made. The drawings in the nature of the case are merely diagrammatic approximations of the density or relative density of the. negatives. If the drawings be looked at with the eyes nearly closed, and especially from the back of the sheet, a better effect will be obtained.

The invention relates primarily to a process and instrumentalities whereby negatives having true and correct color tones or color values for making color plates for three color work, or other color work, are produced photographically without hand-work of any kind. By my process there are provided or produced corrective plates which are used 1n connection with the ordinary color negatives (which negatives are incorrect or untrue in color values) whereby without hand-work or manipulation printing plates are produced which are true or correct in their color values.

Stating the invention generally, but somewhat more in detail, a color negative (which may be conveniently called the primary egative) is made in the usual manner, but reversed, representing -the usual deficiencies or untruth in color values which are inherent in such negatives, and a reverse mask negative is made from the original, hav- .ing opaque or color value parts or areas. This mask negative is then placed in the camera and registered with the image of the original from the lens, and a sensitive plate is placed in contact with this mask negative, to make a corrective plate for use in connection with the primary negative in producing a color printing plate of true or correct color value. An exposure is made on this sensitive plate through the mask negative which will give a positive having in certain of the color regions the degree of opacity needed to correct the primary or untrue negative. From the primary negative and the corrective positive plate in reg ister and in contact a positive is made and from this the color printing plate is made. I find in practice that I can use the primary negatives for the blue and magenta as masks for making the corrective positives.

It will be understood that the preceding general definitions of the invention are explanatory and exemplary and not restrictive in character.

lVhen the color plates are half-tone plates, the half-tone screen may be employed at any desired or suitable point in the making of the printing plates, as may be found convenient and desirable, and this may be in accordance with known practice so far as concerns the present invention.

Referring now in full detail and by way of example to the resent preferred manner of carrying out tie invention, it will be described and explained in connection with the making of plates for three-color or, at a later point for four-color work. In producing three-color or four-color process work with the proper colored inks, it will usually be found that only the magenta plate or negative (sometimes called the red plate) and to a lesser degree the yellow plate or negative stand in need of correction as to their color values or (in the negative) the relative degree of opacity. The blue printing plate if properly made should be true and adequate without correction.

The magenta color negative 01- plate.

Referring primarily to the process of making the printing plate for the magenta color (whlch is frequently termed the red plate), the corrections are required principally in the regions or parts of the plate representing the greens of the original and to a lesser extent in the parts or regions representing the blues of the original. That is, the green and blues of the original are to some extent improperly and incorrectly present in the color tones of the magenta negative as ordinarily made.

At this time, or any other suitable time, an ordinary or primary negative 15 for the magenta color will be made (Fig. 4), this negative having the usual deficiencies and errors in color values as just defined.

To remove or correct the deficiencies and incorrectnesses of this negative (already referred to as the primary negative), I make in the camera a negative, conveniently styled a mask negative 16, which is a reversed negative of the blues, primary and secondary (regions 5, 6 and 7 of Fig. 1), of the original, in this case the color chart of Fig. 1, this mask negative being shown in Fig. 2.

As already stated, a color chart or blocked colors are used in the drawings for the sake of clearness as the principle is the same as in copying a painting, a colored picture, or any art or commercial subject. In Fig. 1 the blocks of the respective primary and Inn secondary colors are marked by name and are alsm provided with reference numerals,-

which numerals are applied throughout the diagrams of the negatives and corrective plates in the successive figures to the corre- 1 sponding color values or color areas.

Accordingly the white is indicated by 1, magenta by 2, red by 3, yellow by 4, reen by 5, blue by 6, violet by '7 and black by 8.

This negative is made by placing a panchromatic or red sensitive plate in the camera with the glass side toward the lens and exposing on it from the original through a red filter. The purpose of reversing the mask negative 16'is so that later the corrective positive may be made through it in the The corrective plate 17 of Fig. 3 is de- I veloped and dried and thereupon is placed in contact with the primary negative 15 shown in Fig. 4, image side to image side and with the images in register. The corrective plate and primary negative in this relation are then used as a single instrumentality in making a. true color value printing plate, in any suitable way, as by making a plate direct, or'by first making a positive from said corrective or, in any suita le manner which is known to the art or is otherwiseadequate. It will be understood, as already indicated, that the magenta negative will be made in reverse the same as the mask, but for convencamera, by placing a light sensitive plate ience and clarity of illustration this feature and the mask in contact in the camera and making an exposure on the sensitive plate through the mask.

1 This masknegative 16 is developed and dried in the usual manner, and is then placed back in the camera and positioned'so that it d will register with the image of the original. I then place a green sensitive plate in the camera immediately behind the mask nega-.

tive 16, and with the sensitive side of .the plate in contact with the image side of the mask negative 16, and expose from the original on the green sensitive plate through the mask negative, using a green filter.

The result of this exposure when developed is a positive or corrective plate 17 of the green, and to a lesser extent of the blue green or cyan blue (as shown in Fig. 3), it being remembered that the magenta plate has to be brought up or made more ellicient in the greens 5 and in the blues 6 to a lesser extent. It will be noted, by reference to Figs. 1 and 2, that this positive or corrective plate 17 of Fig. 3 is not in any way contaminated with whites 1. yellows 4, or blacks 8 of the original, due to the masking of the whites and yellows by the negative 16 of Fig. 2, and to the non-reflective property of the blacks, but this positive or corrective plate 17 will contain or represent only the green and the blue green color values.

From Fig. 2 it will be seen that in the mask negative 16 the white 1, magenta 2, red 3, and yellow 4, are opaque to such an extent as to prevent the light image from the original or copy penetrating those parts of the mask and thus acting on the corrective plate in the corresponding parts. In other words the white, magenta, red and yellow rays from the original will be cut off by the mask 16 from acting on the sensitive surface of the corrective plate 17. Furtherdoes not photograph.

is omitted from the drawing.

From Fig. '1 is will be'seen that the primary negative is deficient in the greens 5, which are of relatively small or slight opacity, and thatthe blues 6 are of insufficient ensity or opacity, although more dense or opaque than the greens. In the corrective plate 17, it will be noted that the greens 5 are of rather high density or opacity and such that when combined with the prImary glate and primary negative,

ne ative (as by contact) they are substantia ly of similar density or opacity to the White 1 and yellow 4 of the primary nega tive 15 of Fig. 4, and that the blue 6 of the corrective plate 17 is of intermediate density or opacity, but such as when combined with the primary negative 15 will also give substantially the same density as the white 'in the primary negative. When the primary negative 15 and the corrective plate 17 are superposed in contact, the efiect will be as shown in Fig. 5, which, as just indicated, represents the correct degrees of opacity or'the correct color value negative 19 made therefrom. In this negative the whites 1, yellows 4, greens 5 and blues 6 are all of uniform density while the magenta 2, red 3 and violet 7 are clear. The black 8 is also clear, as it is not necessary to mask it, due to its non-actinic property. The succeeding steps in'the process of making the magenta color printing plate may be in accordance with known and established practice and may vary as desired. For example, a positive may be made from the true color value negative 19 of Fig. 5, the half tone screen may be employed in the process, and the other steps, such as etching, forexample, may be performed in any usual or acceptable manner.

The yellow negative. or printing plate.

At this time, or subsequently, an ordinary or primary negative 24 for the yellow color will be made in the usual manner. This ne ative will have the usual deficiencies 5111f errors in color values, as represented in its various degrees of opacity, and

will be corrected by steps and instrumen-' talities similar to those employed for the magenta negative or late.

Referring now in etail to the making of the yellow printin plate, the same mask negative 16 as is shown in Fig. 2 may be employed (as negative 16 is opaque to cut out the yellow 4: as well as the magenta 2). In actual practice, however, I prefer the primary magenta negative 15 (Fig. 4) as the mask negative for making the corrective late for use in getting the true color yelow printing plate, and as was the case in making the magenta negative 19, this mask negative 16 is placed in position in the camera in register with the image of the original. An ordinary sensitized plate is placed in the camera, with its sensitive surface in contact with the image-bearing surface of the mask negative 16, and is exposed upon through the mask and through a violet filter. When this plate 21 is developed, the result obtained is illustrated diagrammatically by Fig. 6. The color correction in this case is principally in the violets 7 of the original, which is the principal correction required for the yellow printing plate, at least in many originals, together with some correction in the blue 6, as indicated by the relatively shaded portions of the diagram of Fig. 6.

It is frequently desirable, however, in fine work to correct the yellow printing plate in the parts or region of the magenta in addition to the correction in the violet parts or regions as shown in Fig. 6. In this case, a different mask negative is made (and is employed instead of that of Fig. 2) by using a green sensitive plate and the green color filter. This will give upon development of the plate a mask negative 15 as shown in Fig. 4, wherein all the colors or color re gions are opaque or partially so, except the viqlet 7, the black 8, and the magenta 2 and re The mask negative15 of Fig. 4 (which is preferably the primary negative for the magenta) is employed in the same manner as the other mask negative 16 already described, that is, it is placed in the camera with a light-sensitive plate, which has its sensitive surface in contact with the imagebearing surface of the mask negative 15. This sensitized plate when developed produces the corrective plate 23 of Fig. 7 and this makes a complete or perfect correction for the primary negative 24 for the yellow printing plate. The primary yellow negative 24 is shown by Fig. 8, wherein the white 1 is dense or entirely opaque, and the magenta 2, the cyan blue 6, and the violet 7, are of intermediate degrees of density or opacity, the violet 7 being of least density or opacity.

Fig. 9 represents the true or correct color value negative 25, from which the yellow printing plate is to be made, and is produced in substantially the same manner astlie correct color value negative 19 for thema enta color of Fig. 5, that is, the original or primary yellow negative 24 of Fig. 8 and the corrective plate 23 of Fig. 7 are superposed in register and in contact, and the correct or true color tone negative 25 of Fig. 9 is the result.

From this correct color tone negative 25 the yellow printing plate is made by such further steps as may be required or desired, such steps being known to the art. For example, a positive may be made from negative 25, the half-tone screen may be emp-lodyed at any desired point in the process an the usual or other adequate etching and other r uisite or advisable steps or processes will e employed.

As already stated, the primary negative for the blue printing plate, if well and properly made, will be very nearly absolutely correct in color tone values and will not need correction for even very fine work. If such correction is needed in any case, the application of my process thereto will be obvious from the foregoing.

Application of process to four-color work.

In four-color work (that is, work wherein magenta, yellow, blue and black color plates are employed), the same principle or process as already described is generally applicable. The main difference is that in four-color work it is desirable to eliminate a portion of the bla'ck 8 in the yellow printing plate and in the magenta printing plate, but not in the blue printing plate. Accordingly, to effect this partial elimination or toning down of the blacks in these two rinting plates, the correction positives 1 for the magenta, and 21 or 23 for the yellow, are

more fully exposed through their respective mask negatives 16 or 15. In fact, in practice they are over-exposed to such an extent as to bring out a little action in the black 8 itself.

The corrective plate or positive 26 for the magenta negative, made in the manner just described, that is, with the blacks 8 partly brought out, is shown diagrammatically in Fig. 10. It will be noted that it differs from the corresponding corrective plate 17 for three-color work, which is shown in Fig. 3, in that the black 8 in the plate 26 of Fig. 10 is more or less dense or opaque, as already described, and the green parts 5' and blue parts 6 of Fig. 10 are also relatively somewhat more dense or opaque than the corresponding parts of Fig. 3.

When the corrective plate or positive 26 of Fig. 10 is added to the primary magenta negative 15, which is shown in Fig. 4, and in the manner already described in connecblacks 8 are partly brought out and are corrcspondingly reduced or eliminated in equivalent degree from the magenta printing plate.

The same principle and process may be applied for this four-color work in the case of the correction of the negative for the yellow rinting late, which consequently need not e descri d in detail. It may be stated briefly, if exposure is made through the mask negative 15 of Fig. 4 to such an extent as to partially photogra h the black parts or regions ,8 of the original, the corrective plate 28 thereby produced is diagrammatically represented by Fig. 12. It will be notedthat this diflers from the corresponding corrective plate23 of Fig. 7, in that the black 8 is to some degree dense or opaque, and that the violet 7 blue 6, and magenta 2 regions are relatively somewhat more dense or opaque than the corresponding regions of plate 23.

i In Fig. 13 is shown the true or correct color tone negative 29 for the yellow plate for four color work, made by means of the corrective plate of Fig. 12 and the origlnal yellow negative of Fig. 8.

Making the negative. for the black color a plate.

In producing the black color negative for four-color work, an ideal black negative may be made by employing the mask negative 16 of Fig. 2, and making therewith a compensating or corrective plate as follows:

The mask negative 16 is positioned in the camera so as to register with the image of the original from the lens, and a reen sensitive plate is placed behind it an in contact there-with, the sensitive side of the plate being in contact with the image-bearing side of the mask negative. An exposure is then made from the original through the mask 16, successively through the green color filter and the violet color filter, part of the exposnre being made through each 0t these filters. When this sensitive plate is de- (as shown by 30 1n Fig. 14:), the mask negative 16 of Fig. 2 being a negative of the blue. In this case again the blacks 8 do not photograph by reason of absence of actinic action in the black. It themasknegative 16 of Fig. 2 and this corrective plate 30 be then placed together so that their imagebearing faces are in contact, the combination'will make a practically perfect black negative, that is, a negative for making the black printing plate. These two in contact and the negative resulting therefrom are represented dia rammatically in Fig. '15, wherein the blue (s alone are transparent or photographically etl'ective.

From the foregoing it will be obvious to those skilled in the art that the process and instrumentalities of my invention are adapted to preparing or-making true tone color printing plates for printing in five, six, seven or more colors, the corrective plates (which are simply positives of certain colors made directly from the original by photographingthrough a mask negative) may be used for making the severalrespecthe colors plates required in the particular process- For example, the corrective plate for the green, in processes were the green is printed directly and is not a derived or secondary color as 1t is lIl three-color and four-color work. Thls positive or corrective plate, it

will be understood, represents only the green color values of the original and is not contaminated with either the white or black color values of the original.

The corrective plate for the yellow color values of the original, being in like manner a positive of the violet color values, may be used to make a violet printing plate in the same way. A positive of the red color value may be also'made in like manner or on the same principle, and correspondingly for any other colors which it is desired to print directly.

The term indirect method of color work is generally applied to that method, where a continuous tone negative is first made from the copy for each color to be printed. From these continuous tone negatives, continuous tone positives are made, and from these posior ot er image-bearing plate in the camera,

a coating of collodion, which forms a translucent film or layer, which will efi'ectively prevent halation.

Wet printing in two or more colors. For wet printing it is desirable in two color work, as well as in work .of more colors, that the ink from the different impressions does not superpose any more than is absolutely necessary. In other words, it is not desirable to print one heavy color over another heavy color. This has been largely overcome heretofore in two-color work, and particularly in four-color work, by hand work being employed on the plates to eliminate the undesirable colors. For instance in a two-color subject wherein Persian oran 'e and black are used, it is necessary ,for t e best results to eliminate the Persian orange from beneath the blacks, and as juststated, this is accomplished in the present practice by hand work.

I have devised a newmethod of doing this whereby the hand work is eliminated as follows:

I first make a special mask negative, using a violet filter on a plain or ordinary sensitive plate, or on occasion I use a green filter on a green sensitive plate, using either one as may be most advantageous with any particular copy or original. This mask negative after it is developed and dried is put into the camera and registered with the image coming through the lens. 'I-then place a red sensitive plate in contact with this mask, usinga red filter in' the lens, and make an exposure, which upon development gives me a positive'of the red without being contaminated with either white or black. This positive is used to make the red or Persian orange printing plate and if it is properly exposed and developed it will give a result which will require no hand work to produce satisfactory results.

The black negative is usually made through a red filter on a red sensitive plate without a mask. From this negative a positive is made by the ordinary methods. A positive so made from the black negative in conjunction with the positive made in the camera direct from the copy constitutes the two positives which are used to make the half-tone plates when the indirect method is used.

It will be understood that changes may be made in the various steps and in the par ticular manner of carrying out or practicing the same, without departing from the principles of the invention and without sacrificing its chief advantages.

What I claim is 1. The process of making a correct color tone negative for use in making color printing plates which comprises making a color negative from an original and using same to make a correct color value negative from which a color printing plate is made.

2. The process of making a correct color one negative for use in making color printing plates which comprises making a color negative from an original and using same to make a correct color value negative of a difnegative of one of the primary color valuesv of an original and using same to make a cor-' rect color value negative from which a color printing plate is made.

4. The process of making a correct color tone negative for use in making colorprinting plates which comprises making a color negative from an original and uslngsamc to make a correct color value negative of one of the primary colors of the original from v which a color printing plate is made.

5. The process of making a correct color tone negative for use in making color printing plates which comprises making a color negative of one of the primary color values of an original and using same to' make a correct color value negative of another of the primary colors of the original from which a color printing plate is made.

6. The process of making a color negative from an original, making therefrom a corrective positive, from "an original, making therefrom a corrective positive, and using the corrective positive to make a correct color value negative from which a color printing is made.

7. The process of making a color negative from an original, makin therefrom'a corrective positive, and uslng the corrective positive to make a correct color value negative of a different color in the original, from which a color printing plate is made.

8. The process of making a color negative of one of the primary color values of an original, making therefrom a corrective positive, and using the corrective positive to make a correct color value negative from which a color printing plate is made.

- 9. The process of making a color negative of one of the primary color values of an original, making therefrom a corrective positive, and using the corrective positive to make a correct color value ne ative of another of the primary colors 0 the original from which a color printing plate is made.

10. The process of making an ordinary color value negative of one color of an original and making a color value negative of another color of the original and using same to correct errorsof color value in the firstmentioned color value negative.

11. The process of makin an ordinary color value negative of one co or of an original and making a color value negative of another color of the original, making a corrective positive therefrom and using same to correct errors of color value in the first-mentioned color value negative.

12. The process of making an ordinary color value negative of one primary color' of an ori inal and making a color value negative 0 another color of the ori inal and using same to correct errors of co or value in the first-mentioned color value no ative.

13. The process of making an or' inal-y color value negative of one color'of an originaland making a color value negative of another primary color of the original and ing a true color value printing plate.

15. The process of making an ordinary color value negative of one primary color of an original and making a color value negative of another primary color of the original, making a corrective positive therefrom and employing the corrective plate and the firstmentioned negative as a single instrumentallity in making a true color value printing p ate.

16. The process of makin an ordinary color value negative of one color of an original and making a color value negative of another color of the original, making a corrective positive therefromand bringing the coirective positive and the first-mentioned negative into contact and register to make a true color tone printing plate.

17. The process of making an ordinary color value negative of one color of an original and making a color value negative of another color of the original, making a corrective positive therefrom and using same to correct errors of color value in the firstmentioned color value negative while they are used together to make a true color value negative for use in making a printing plate.

18. The process of making an ordinary color value negatlve of one color of an original and making a color value negative of another color of the original, making a corrective positive therefrom and employing the corrective plate and the first-mentioned negatlve as a single instrumentality in making a true color value printing plate While they are used together to make a true color viilp: negative for use in making a printing p a 19. The process of making an ordinary color value negative of one primary color of an original and making a color value negative 0 another primary color of the original, making a corrective positive therefrom and employing the correctiveplate and the first-mentioned negative as a single instrumentality in making a true color value printing plate while they are used together to make a true color value negative for use in making a printing late.

20. The process 0 making a negative from the colored original, making a corrective plate and combining the two as an instrumentality in making a printing plate. 21. The process of making a negative of one of the primary colors of a colored original, making ;a corrective plate and combining the two as an instrumentality in making a printing plate.

22. The process of making a negative from a colored original, making a corrective plate from another color of the original and combining the two as an instrumentality in making a printing plate.

23. The process of making a negative from a colored original, making a corrective plate from another color of the original and combining the two as'an'instrumentality in makin a printing plate of the same color as sai negative.

1 24. The process of making a negativeof one of the primary colors of a' colored original, making a corrective plate from another primary color ofthe original and combining the two as an instrumentality in making a printing plate.

25. The process of making a negative of one of the primary colors of a colored original, making a corrective plate from another primary color of the original and combining the two as an instrumentality in making a printing plate of the same primary color as said negative.

26. The process of making a reversed color negative from an original, making therefrom a corrective positive, and using the corrective positive to make a correct color value negative from which a color printing plate is made. 4

27. The process of making an ordinary' color value negative of one color of an original and making a reversed color value n'ega-' tive of another color of the original, making a corrective positive therefrom and using the same to correct errors of color value in the first-mentioned color value negative.

28. The process of making an ordinary color value negative of one color of an original and making a reversed color value negative of another color of the original, making a corrective positive therefrom and employing the corrective plate and the first-mentioned negative as a single instrumentality in making a true color value printing plate.

29. The process of making an ordinary color value negative of one color of an original and making a reversed color value negative ofanother color of the original, making a corrective positive therefrom and bringing the corrective positive and the first-mentioned negative'into contact and register to make a true color tone printing plate.

30. The process ofv making a color negative of a colored original, making a color -p negative of another color from said original and employing said second negative as a mask in correcting the first-mentioned color negative.

31. The process of making a color negative of a colored original, making a color negative of another color from said original and employing said second negative as a mask in making a corrective plate and employing said corrective plate in correcting the first-mentioned color negative.

32. The process of making a color nega tive of acolored'original, making a color negative of another color from said original using said second color negative in the camera as a mask for a sensitized plate and photographing on the plate the original through the mask, and using said plate in correcting the color value of the first-men tioned color negative.

33. The process of making a color negative of a coloredoriginal, makin a color negative of another color from sai original using said second .color negative in the camera as a mask for a sensitized plate and photographing on the plate the original through the mask, and using said plate in contact with said first-mentioned color negative in making a correct color value printing plate.

34:. The rocess of making a true color value printing plate which comprises as a step making a corrective mask negative in which the white of a colored original and all color values except those required for correcting a given color are'opaque.

35. The rocess of making a true color value printing plate which comprises as a step making a corrective mask negative in which colors required'to correct the plate are translucent and can be photographed through the mask.

36. The process of making a true color value printing plate which comprises as steps, making a mask with a filter for one color of an original and photographing on a sensitized plate through said mask with a filter for another color, and employing the late so. photographed in making the printmg plate.

37. The process of making a true color value printing plate which comprises as steps, making a mask with a filter for one color of an original and photographing on a sensitized plate through said mask with a filter 'for another color to make a corrective plate for, use in making a printing plate.

38. The process of making a true color value printing plate which comprises as a step making a positive of a color of an ori inal by photographing directly from the original through a mask.

39. The process of making a 'true color value printing plate which comprises as a step making a positive of a color of an original by photographing directly from the original through a mask representing another color of the original.

40. The process of making a true color valueprinting plate which comprises as a step making a positive of a primary color of an original by photographing directly from the original through a mask.

41. The process of making a true color value printing plate which comprises as a step making a positive of a primary color of an original by photographing directly from the original through a mask representing another primary color of the original.

42. The process of making a true color value printing plate which comprises as a step making a positive of a color of an original by photographing directly from the original through a mask representing a color of the original complementary to said first-mentioned color.

43. As an instrumentality in making a true color tone printing plate, a negative of a color value of an original and a corrective plate in contact tl1erewith. 1

In testimony whereof, I have signed my name to this specification.

JOSEPH A. H. HATT. 

